diff --git a/p2p/base/basic_packet_socket_factory.h b/p2p/base/basic_packet_socket_factory.h
index f4282e1ad0..396a8ba4eb 100644
--- a/p2p/base/basic_packet_socket_factory.h
+++ b/p2p/base/basic_packet_socket_factory.h
@@ -23,12 +23,13 @@
 #include "rtc_base/socket.h"
 #include "rtc_base/socket_address.h"
 #include "rtc_base/socket_factory.h"
+#include "rtc_base/system/rtc_export.h"
 
 namespace rtc {
 
 class SocketFactory;
 
-class BasicPacketSocketFactory : public PacketSocketFactory {
+class RTC_EXPORT BasicPacketSocketFactory : public PacketSocketFactory {
  public:
   explicit BasicPacketSocketFactory(SocketFactory* socket_factory);
   ~BasicPacketSocketFactory() override;
diff --git a/p2p/base/connection.h b/p2p/base/connection.h
index c0a19b510f..4e6c7d91be 100644
--- a/p2p/base/connection.h
+++ b/p2p/base/connection.h
@@ -29,6 +29,7 @@
 #include "rtc_base/network.h"
 #include "rtc_base/numerics/event_based_exponential_moving_average.h"
 #include "rtc_base/rate_tracker.h"
+#include "rtc_base/system/rtc_export.h"
 #include "rtc_base/weak_ptr.h"
 
 namespace cricket {
@@ -56,7 +57,7 @@ struct CandidatePair final : public CandidatePairInterface {
 
 // Represents a communication link between a port on the local client and a
 // port on the remote client.
-class Connection : public CandidatePairInterface {
+class RTC_EXPORT Connection : public CandidatePairInterface {
  public:
   struct SentPing {
     SentPing(absl::string_view id, int64_t sent_time, uint32_t nomination)
diff --git a/p2p/base/p2p_constants.h b/p2p/base/p2p_constants.h
index 07257d5e18..d51ee17a07 100644
--- a/p2p/base/p2p_constants.h
+++ b/p2p/base/p2p_constants.h
@@ -40,7 +40,7 @@ extern const size_t ICE_PWD_MAX_LENGTH;
 
 RTC_EXPORT extern const int ICE_CANDIDATE_COMPONENT_RTP;
 RTC_EXPORT extern const int ICE_CANDIDATE_COMPONENT_RTCP;
-extern const int ICE_CANDIDATE_COMPONENT_DEFAULT;
+RTC_EXPORT extern const int ICE_CANDIDATE_COMPONENT_DEFAULT;
 
 // RFC 4145, SDP setup attribute values.
 extern const char CONNECTIONROLE_ACTIVE_STR[];
diff --git a/p2p/base/port.h b/p2p/base/port.h
index d746f3de02..31091eb273 100644
--- a/p2p/base/port.h
+++ b/p2p/base/port.h
@@ -176,7 +176,7 @@ typedef std::set<rtc::SocketAddress> ServerAddresses;
 // Represents a local communication mechanism that can be used to create
 // connections to similar mechanisms of the other client.  Subclasses of this
 // one add support for specific mechanisms like local UDP ports.
-class Port : public PortInterface, public sigslot::has_slots<> {
+class RTC_EXPORT Port : public PortInterface, public sigslot::has_slots<> {
  public:
   // INIT: The state when a port is just created.
   // KEEP_ALIVE_UNTIL_PRUNED: A port should not be destroyed even if no
diff --git a/p2p/base/stun_port.h b/p2p/base/stun_port.h
index 13970070ed..380dbecd2d 100644
--- a/p2p/base/stun_port.h
+++ b/p2p/base/stun_port.h
@@ -22,6 +22,7 @@
 #include "p2p/base/port.h"
 #include "p2p/base/stun_request.h"
 #include "rtc_base/async_packet_socket.h"
+#include "rtc_base/system/rtc_export.h"
 
 namespace cricket {
 
@@ -31,7 +32,7 @@ static const int INFINITE_LIFETIME = -1;
 static const int HIGH_COST_PORT_KEEPALIVE_LIFETIME = 2 * 60 * 1000;
 
 // Communicates using the address on the outside of a NAT.
-class UDPPort : public Port {
+class RTC_EXPORT UDPPort : public Port {
  public:
   static std::unique_ptr<UDPPort> Create(
       rtc::Thread* thread,
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index 4a9a5463ed..7d236bc12c 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -839,7 +839,7 @@ rtc_library("net_helpers") {
     "net_helpers.cc",
     "net_helpers.h",
   ]
-  deps = []
+  deps = [ "system:rtc_export" ]
   if (is_android) {
     deps += [ ":ifaddrs_android" ]
   }
@@ -1389,6 +1389,7 @@ rtc_library("net_helper") {
     "net_helper.h",
   ]
   absl_deps = [ "//third_party/abseil-cpp/absl/strings" ]
+  deps = [ "system:rtc_export" ]
 }
 
 rtc_library("socket_adapters") {
diff --git a/rtc_base/net_helper.h b/rtc_base/net_helper.h
index 758c0faad9..2dce91196c 100644
--- a/rtc_base/net_helper.h
+++ b/rtc_base/net_helper.h
@@ -13,13 +13,14 @@
 #include <string>
 
 #include "absl/strings/string_view.h"
+#include "rtc_base/system/rtc_export.h"
 
 // This header contains helper functions and constants used by different types
 // of transports.
 namespace cricket {
 
-extern const char UDP_PROTOCOL_NAME[];
-extern const char TCP_PROTOCOL_NAME[];
+RTC_EXPORT extern const char UDP_PROTOCOL_NAME[];
+RTC_EXPORT extern const char TCP_PROTOCOL_NAME[];
 extern const char SSLTCP_PROTOCOL_NAME[];
 extern const char TLS_PROTOCOL_NAME[];
 
diff --git a/rtc_base/net_helpers.h b/rtc_base/net_helpers.h
index 631c6348a7..478cec3eed 100644
--- a/rtc_base/net_helpers.h
+++ b/rtc_base/net_helpers.h
@@ -20,6 +20,7 @@
 #endif
 
 #include "absl/strings/string_view.h"
+#include "rtc_base/system/rtc_export.h"
 
 namespace rtc {
 
@@ -28,8 +29,8 @@ namespace rtc {
 const char* inet_ntop(int af, const void* src, char* dst, socklen_t size);
 int inet_pton(int af, absl::string_view src, void* dst);
 
-bool HasIPv4Enabled();
-bool HasIPv6Enabled();
+RTC_EXPORT bool HasIPv4Enabled();
+RTC_EXPORT bool HasIPv6Enabled();
 
 }  // namespace rtc